Automatic variable delivery fuel pump



Dec. 9, 1941. A. J. RICHARDS AUTOMTIC VARIABLE DELIVRY FUEL ,PUMP

Filed Sept. 9, 1940 2 Sheets-Shea?I l l. mm. ma NGN.

Dec. 9, 1941. A. J. RICHARDS AUTOMATIC VARIABLE DELIVERY FUEL PUMI?Filed Sept. 9, 1940 2 ShemEs-Sheeil 2 E nventor Patented Dec. 9, 1941Arthur nichel-ds, Lansing, Mich.

Application September 9, 1940, Serial No. 355,927`

10 Claims.

This invention relates to pumps and in particular to variable-deliveryconstant-pressure pumps.

One object of this invention is to provide a .variable-delivery pumphaving means associated therewith for maintaining a substantiallyconstant pressure in the output circuit of the pump regardless of thespeed at which the pump is driven.

Another `object is .to provide avariable-delivery constant-pressure pumpemploying a bellows mechanism for pumping the fluids and having meansresponsive to the increase of pressure in the output circuit of the pumpfor varying the stroke of the pump, thereby maintaining a substantiallyconstant pressure in the output circuit thereof.

Another object is to provide a variable-delivery constant-pressure pumphaving an automatically-adjustable lostmotion connection between theactuating mechanism and the pumping mechanism, this lost motionconnection being automatically adjustable in response to an increase inpressure in the output circuit of the pump so that the pump stroke isautomatically reduced with an increase in output pressure while theactuating stroke remains the same.,

Another object is to providea variable-deliv ery constant-pressure pumpas set forth in the Ypreceding objects wherein a thermostatic element.is interposed for automatically increasing the stroke-varying pressurein order to overcome the vapor lock condition sometimes occurring whenthe motor is operated under higher than normal temperatures, so that thepump will continue to operate at full stroke until the output pressurerises to a higher level than the normal level at which thestroke-reducing mechanismA becomes operative at normal temperature.

In the drawings:

Figure 1 is a central vertical section through a preferred embodiment`of the pump of this invention.

Figure 2 is a horizontal section approximately along the line 2-2 inFigure 1 showing the lost motion connection which -is automaticallyadjustable to provide a variable str oke for the pump. 1 I

Figure 3 is a vertical section taken along the line 3-3 in Figure 1 andcomprising a longitudinal section through the lost motion connection.

Figure 4 is a horizontal section through the upper bellows of the pumptaken along the line 4 4 in Figure 1. l

Figure is a fragmentary vertical section'of the upper part of Figure 1,but showing the thermostatic mechanism after it has operated in responseto a predetermined' rise in temperature to increase the pressure levelat which the stroke reduction becomes effective.

Figure 6 is a fragmentary view of a modification of Figure 1 employing adome-like diaphragm instead of a bellows.

General arrangement y In general, the variable-delivery.constantpressure pump of this invention consists of a. pumping device,such as a bellows, which is actuated from a cani shaft through a` lostmotion connection. This-lost motion connection determines the strokewhich shall be applied to the pumping mechanism independently of thestroke applied by the cam shaft.

The lost motion connection is varied automatically in its adjustment inresponse to the rise of pressure in the output circuit of the pump. Whenthe pressure increases4 to a predetermined level, a cam mechanismpermits the lost motion device to open more or less, according t'o theoutput pressure attained. As the lost motion device opens, the strokeactually applied to the pumping mechanism is automatically' reduced eventhough the stroke of the cam shaft remains constant.

As a further feature, the pump is equipped with a thermostatic devicewhich automatically increases the stroke-reducing pressure toa higherlevel in response to a rise in temperature. This featurel is especiallyimportant in fuel pumps, where high operating temperatures often createvapor locks and consequently prevent the pump from delivering the properamount of fuel to the engine. With the thermostatic ldevice of thisinvention. the operating level of the pump is automaticallystepped up toa higher pressure level when the temperature reachesa predetery minedheight.

The variable-delivery constant-pressure pump of this invention isparticularly valuable in use as a fuel pump for internal combustionengines,

4especially gasoline engines. In s'uch engines, it

is very important that a reasonably constant output pressure shall bemaintained, so that the engine will always be supplied with fuelthroughout y a wide range of operating conditions from slow designated33 (Figure 3),.

invention, however, the static pressure in thev output circuit remainssubstantially constant regardless of thepower input variation over awide range of speeds.

and' contraction of the upper bellows and has also been veried by actualexperimental tests.

vMoreoverI an outlet pressure adjusting screw is additionally providedto enable outlet pressure of the pump to be adjusted to suit individualcar-4 buretor requirements, and also to` adjust the Y thermostaticdevice.

Pump construction Referring to the drawings in detail, Figure 1 shows apreferred embodiment of the pump of this invention as consisting of acasing having an intake connection and an intake passage duced diameterportion 25 of a pin 26, the enlarged portion of which enters a. bore 21in an internal tubular projection 23 of the pump casing |0. -The tubularprojection 23 extends downwardly from the partition member'23 forming aninternal bulkhead in the pump casing i0, and serves as a guide for thereciprocation of the pin y26. The opposite end of the pin 26 is enlargedas at 30 to clamp a and 23.

The yoke 3| is provided with ears 32 carrying a shaft 33 which in turnengages the driven arm yoke 3| against the disks 22 '34 by passingthrough a bore 35 therein (Figure 2). The driven arm 34 at its oppositeend'is provided with an eye 36 which is slipped over a sleeve-likeprojection 31 within the driven cam member 33 of the lost motion devicegenerally The end of the sleeve portion 31 is upset as at 40 to securethe arm 34 tightly to the driven cam member 33.

'I'he driven cam member 33 is provided with triangular tongues 4|(Figure 2) engaging corresponding triangular notches 42 in a driving cammember 43. The latter is provided with an internal sleeve portion 44carrying the intermediate portion 45 (Figure 3) of a driving arm 43. Theinner end of the driving arm 46 is bent as at 41 and has a coil spring43 connected thereto as at 43 (Figure 1), the opposite end of the'spring` being anchored as at l0 to the lug 5| on 1 the inside of thecasing cover plate 52. The latter is secured by the screws 53 to therim-54 of the casing l0, thus serving as aclosure for the latter. 'I'heouter endv of the driving arm 46 is arched as at 35 (Figure 1) and ymounted upon the cam shaft 51.

engages a cam 53 The driving and driven cam portions 43 and 33 (Figure3) are providedwith bores 53 and 33 y respectively. which receive ashaft 30 secured within the casing bores 6| and 32 by the pins 63 1extending through the end holes 34 in the shaft 33.' A washer 6l isinterposed between the driving cam member 43 and the Yinterior of thepump i casing I0. A coil spring 33 within the driving This results fromthe variation' of the pump strokein response to the expansion upon whichis mounted an arm secured there-v and driven cam members 43 and 33serves to i urge these members apart, thus tending to cause thetriangular tongues 4| in the driven cam 33 to withdraw from the notches42 in the driven cam member 43. When this occurs. only a portion of thestroke imparted to the driving cam member by the cam 56 and driving arm46 will be transmitted to the driven cam 33 and driven arm 34, andthence to the pumping diaphragm I1. 1

'I'he driven cam 33 is provided with a conical end surface 61 which isengagedby the conical end 63 of an axially'reciprocable cam rod 63 whichis reciprocable in the aligned bores 10 and 1| of the tubular guideportions 12 and 13 extending in opposite directions from the partitionmember 23 (Figure 1). The upper en d of the cam rod 63 has a reduceddiameter portion 14 to by the enlargement 16.

The arm 15 `extends radially inward and at its inner end is providedwith a bore 11 which surrounds the sleeve portion 13 of the spring cap13,v

the latter` in turn surrounding the reduced dif ameter portion 30 of thepin 3i. Also mounted on the reduced diameter portion 30 and held thereonin a similar way are the twin disks 32 and 83, between which is clampedthe end 34 of the upper bellows 35. The opposite end of the upperbellows 35 is clamped against thev partition member 23 by an annularmember 36 also held in position by the screws 2|. The screws 2| alsoserve to retain in position a cover cap 81 for covering the upperbellows 35.and its associated mechanism.

The cover cap 31 is provided with a threaded plug 33 secured thereto asat 33. Threaded into the bore 30 of the plug 33 is an adjusting screw 3|equipped with a lock nut 32 for holding it in any adjusting position.The lower end ofthe adjusting screw 3| is provided with a reduceddiameter portion 33 terminating in an enlarged head 34 which serves as aretaining flange for a disk 35 having an aperture 31 therein. Abimetallic thermostatic disk 36 is secured as at 33 .to the adjustingscrew 3|. Extending between the disk 35 and the spring cap 13 isa'compression coil spring 33 which serves to urge the bellows 35 towardits collapsed position. At the same time, the spring 33 also urges thecam rod 63 downward in a direction causing the lost motion connection 38to close and take up its lost motion.

The bimetallic disk 36 is composed of two metallic disks |00 and |0Iheld together at their edges as at I||2 and composed of materials ofdifferent coeicients of expansion. As a consequence.- with a rise intemperature, one disk expands more rapidly than the other, causing theassembly to assume a bowed or. cupped condition, as explained below.

The passage of iiuid from the lower bellows I1 to the upper bellows 35isregulated by the valve disk |03-mounted in the valve body |04, thelatter being provided with a port |03 aligned with,

the port |03 in the partition member 23 (Figure 1). Accordingly, thevalve member |03 opens upon the compression stroke -of the bellows 1,the valve member I5 thereof opening upon the suction stroke.

The partition member 23 (Figure 4) is provided with an outlet port |01opening into an outlet passageway |03 terminating in an outletconnection |03. The outlet conduit thus formed conducts the fluid fromthe interior of the bellows 35 to the pipe leading to the carburetor orother point of utilization of the .iiuid pumped by the pump. l In themodication shown'in Figure 6, one or both of the bellows '|1 or 35 isreplaced by a diaphragm ||0. The latter is Vsecured at its outer of theconstruction is the same as shown in Flg` ure 1 and corresponding partsbear similarreference numerals.

Operation In the operation of the pump shown in yFigure 1, the startingof the engine causes the cam .f

shaft 51 and cam 56 to rotate, moving the driving arm 46 up and down andconsequently moving the driven arm 84 and the bellows |'1 up and down,provided the lost motion connection 39 is closed, as shown in FiguresZand 3. This condition will occur when the engine is first started andthere is very little pressure Within the upper bellows 85, permittingthe cam rod 69 to be pushed downward by the coil spring 99, closing thelost motion device 39.

As the bellows I1 expands on the downward stroke of the pin 26, thevalve member |5'moves downward oil its seat and permits fluid to bedrawn through the connection and the passageway I2 through the port I3intothe chamber I6 within the bellows l1. When the pin 26 moves upward,however, and the bellows I1 is thereby collapsed, the fluid within thebellows |1 is forced through the ports |06 and |05 into the interior ofthe upper bellows 85, lifting the Y valve member |03 to open thiscommunication. l Due to the pressure of the fluid forced into theinterior of the upper bellows 85, the pressure thereon is eventuallysufficient to overcome the thrust of the coil spring 99 and expand thebellows 85. This lifts the arm 15 and cam rod 69 when the pressurereaches a predetermined amount. Such an increase in pressure occurs whenthe. amount of fluid being pumped into the bellows 85 is greater thanthe amount of fluid being taken out through .the passageway |08, such aswhen the .pump is` pumping more fuel than the engine is capable of usingup at an idling speed.

When the cam rod 69 rises in response to an increase in pressure withinthe upper bellows 85, the elements 38 and 43 ofthe lost motion device 39are caused to separate under the urge of the coil spring 86 (Figure 3),moving the triangular tongues 4| out of their notches 42.

When this occurs, the arm 46 and member 48 move for a certain distancebefore the edge of the notch 42 encounters the edge of the tongue 4|. Asa consequence, only a part of the stroke of the driving arm 46 istransmitted to the driven arm 34, and the bellows |1 executes only apart of its full stroke.

As a result, the volume of fluid pumped into the upper bellows 85 duringa given time interval is considerably reduced, so that the expansion ofthe bellows 85 is retarded,'provided that fluid is lbeing withdrawn fromits interior through the port |01 and passageway |08y (Figure 4). Y v

In the event that the engine isidling and the fuel is being pumped intothe interior of the bellows 85 much more rapidly than it is being usedpp by the engine, the bellows 85 will be greatly expanded. causing thecam rod 69 to rise through a substantial distance and permit theelements 38 and 43 of the lost motion device 39 to separate to an extentwhere no motion whatever is transmitted from the driving arm 46 to the 4driven arm 34.

kment yagain resumes its upwardly concave condition When, however,enough fuel has been used up by the engine to reduce the pressure withinthe upper bellows 85, the coil spring` 99 forces` the latter downward,and with it, 'the arm 15 and cam rod 69. This action urges the element38 toward the A element 43, thus causing the tongues 4| to enter thenotches 42. When the tongues 4| fully enter the notches 42 (Figure 2),the lost motion is entirely taken up by the lost motion device 39, andthe full stroke of the driving arm 46 is transmitted to the driven army34,

causing the bellows |1 to execute its full stroke. i During very hotweather, the high temperature frequently vaporizes the fuel beingpumped, so that the bellows 85 contains a gaseous vapor instead ofliquid fuel. This gaseous vapor would serve as a vapor lock and soonbring the engine to a halt,'because'although the pressure of the vaporwithin the bellows 85 is still sufficient to expand the latter and raisethe cam rod 69, only gas` and not liquid fuel would be supplied to theoutlet port |01 and passageway |08.. Under these conditions.. theengine` would halt `by its lack of sufllcient fuel.

Toovercome this .vapor lock condition, the engine provides thethermostatic disk mechanism shown in the upper part of Figure l. Atordinary temperatures, the bimetallic disks |00 and |0| will assume theupwardly concave condition shown in Figure l. When a high rise intemperature occurs, however, the vmetallic ele-l ment` |00, with thegreater coefiicient of expansion, will expand more rapidly than themetallic velement |0|, causing the unit 96 to become convex upwardly(Figure 5). Thus the edges ofthe unit 96 press the disk 95 Adownward andthis adsnap action results in a quick and abrupt shift.

from one pressure level to the other as the temperature changes.

The eiect of this additional compression of the coil spring 99 resultsin the necessity for the bellows I1. to pump more fluid into the upperbellowsA 85 to raise the arm 15 and cam rod 69.

and open the lost'motion device 39. The additional fluid thus pumpedrelieves the vapor lock condition and supplies the necessary fluid forthe engine.

vWhen ythe temperature returns to normal, the greater contraction of'the upper element |00 causes it to contract more rapidly than the ele-|00, whereupon the, bimetallic `unit 96 (Figure l) and the pump isautomatically adjusted to .operate the losty motion device 39 at thelower pressure level.

The operation of themodification shown in Figure 6 is similar to that ofthe main vform of the invention shown invFigure l.` `ThisA form of theinvention, however, is useful where onlya short stroke is required andthe expansion of a bellows `is not needed. l

With either form of the invention, the delivery of the pump isautomatically altered by the closing or opening of the lost motiondevice 39,

, thereby causing the output pressure to remain substantially constantregardless of the increaseincrease in the number of pulsations perminute of the bellows I1.

, While I have shown and described my invention in detail, it is to beunderstood that the same is to be limited only by the appended claimsfor many changes 'may be made without departing from the spirit andscope of my invention. j

What I claim is: 1 1. In a variable-delivery pump, a reciprocablepumping device, a driven element connected pumping device, a drivenelement connected thereto, a driving element, a separable strokeing anexpansible device responsive to the attainpressure in said outletcircuit for urging said projection into said recess whereby to closesaid separable connection and increase the stroke of said pumpingmember. l

6. In a variable-delivery pump, a casing, a reciprocable pumping meansassociated therewith having an inlet circuit and an outlet circuit,

a driven arm connected tosaid pumping means, a` power-operable drivingarm, and an interengaging tapered tongue and notch connection interposedbetween said arms.

7. In a variable-delivery pump, a casing, reciprocable pumping meansassociated therewith having an inlet circuit and an outlet circuit, adriven arm'connected to saidl pumping means, a power-operable drivingarm, an interengageable tapered tongue and notch connection interposedbetween said arms, andmeans includment of a predetermined pressure insaid outlet circuit for moving said tongue out of said notch whereby toreduce the stroke of said driven varying device connected between saidelements and including a`pair of separable wedge portions havingengageable surfaces inclined relatively to their direction ofseparation, an outlet circuit connected to said pumping device, andmeans responsive to the attainment of a predetermined pressure in saidoutlet circuit for separating said stroke-varying device whereby toreduce the stroke of said driven element.

3. In a variable-delivery pump, a reciprocable pumping device, a drivenvelement connected thereto, a driving element, a separablestrokevaryingdevice connected between said elements and including interengagingprojections and recesses having mutually engageable surfaces inclinedrelatively to their direction of separation, an outlet circuit connectedto said pumping device, and means responsive to the attainment of apredetermined pressure in said outlet circuit for separating saidstroke-varying device whereby to reduce the stroke of said drivenelement.

4. In a variable-delivery pump, a reciprocable pumping device, a drivenelement connected thereto, a driving element, a separable strokevaryingdevice connected between said elements and including interengagingprojections and recesses having edges angled relatively to theirlongitudinal axes, an outlet circuit connected to said pumping device,and means responsive to the attainment of a predetermined pressure insaid outlet circuit for separating said strokevarying device whereby toreduce the stroke of said driven element.

arm relatively to the stroke of saidA driving arm..

8.` In a variable-delivery pump, a reciprocable pumping device, meansfor reciprocating said pumping device, an outlet circuit connected i tosaid pumping device, means responsive to the.

' attainment of a predetermined pressure in said outlet circuit forreducing the stroke of said pumping device, and means includingsnap-action mechanism responsive to the attainment of -a predeterminedtemperature for abruptly raising said predetermined pressure to a higherpres sure level.

9. In a variable-delivery pump, a reciprocable pumping device, a drivenelement connected thereto, a driving element, a lost motion deviceconnected between said elements, an outlet circuit connected to saidpumping device, means responsive to the attainment of a predeterminedpressure in sai'd outlet circuit for reducing the stroke of said pumpingdevice. resilient means for controlling said;s predetermined pressure,vand means including snap-action mechanism connected to said resilientmeans and responsive to the attainment of a predetermined temperaturefor abruptly altering the thrust thereof whereby to abruptly raise saidpredetermined pressure to a higher pressure level.

10. In a variable-delivery pump, a casing. a reciprocable pumping membertherein having an inlet circuit and an outlet circuit, a driving elementconnected to said Vpumping member, a

5.v In a variable-delivery pump, a casing, a

reciprocable pumping member therein having an. inlet circuit and anoutlet circuit. a driving element connected to said pumping member, adriven element adapted to be connectedto a power source, a separableconnection having a' tapered interlocking projection and recessinterposed between said driving and driven elements,

means for urging said projection out of said recess to separate saidconnection, and means responsive to a decline below a predetermineddriven element .adapted to be" connected to a` power source. a separableconnection having a tapered interlocking projection and recessinterposed between said driving and driven elements, means i'or urgingvrsaid projection out ofsaid recess to separate said connection, meansresponsive to a decline below a predetermined l pressure in said outletcircuit for urging said projection into said recessl whereby to closesaid separable connection and increase the stroke of said pumpingmember, and means reponsive to .v

the attainment oi'-l a predetermined temperaa higher pressure level.

ture for raising said predetermined pressure to J. RICHARDS.

